Referring to FIGS. 1 and 2, a grinding and extracting device of an existing food processor includes a tubular member 1 and a spindle 2. The tubular member 1 surrounds a central axis 10, and includes a tubular main body 11 that tapers from a rear side to a front side thereof, a plurality of angularly spaced-apart protruding ribs 12 protruding from an inner wall surface of the tubular main body 11 and extending along the central axis 10, a metal ring 13 embedded in the inner wall surface of the tubular main body 11 and located at a front end of the protruding ribs 12, a support screen plate 14 projecting rearwardly from a rear bottom edge of the tubular main body 11, an annular flange 15 spaced apart from the front side of the tubular main body 11, a filter member 16 located at a front side of the metal ring 13 and connected between the annular flange 15 and the tubular main body 11, and an elastic ring 17 disposed inside and protruding radially and inwardly from the annular flange 15.
The spindle 2 is inserted into the tubular member 1 and is driven by a drive unit (not shown) to rotate about the central axis 10. The spindle 2 includes a guide entry section 211 disposed above the support screen plate 14, a crushing section 212 extending forwardly and gradually enlarging from the guide entry section 211 to a position proximate to the metal ring 13, a grinding section 213 tapering forwardly from the crushing section 212, a filter section 214 extending forwardly from the grinding section 213 into the filter member 16, and a guide exit section 215 extending forwardly from the filter section 214 and passing through the elastic ring 17. The spindle 2 further includes a guide thread 22 helically wound around the guide entry section 211, a crushing thread 23 helically wound around the crushing section 212, eight spaced-apart grinding threads 24 helically wound around the grinding section 213, and four spaced-apart filter threads 25 helically wound around the filter section 214.
In operation, the spindle 2 is driven to rotate relative to the tubular member 1, and foodstuff is placed at the rear side of the tubular main body 11. The foodstuff is cut into sections by the guide thread 22, and is guided by the same to move forward into the tubular main body 11. The sectioned foodstuff is then crushed through cooperation of the crushing thread 23 and the ribs 12, after which it is ground through cooperation of the grinding threads 24 and the metal ring 13. As the ground foodstuff is guided by the filter threads 25 to pass through the filter member 16, the foodstuff is squeezed to extract juice therefrom, and the extracted juice drips out of the filter member 16 to be collected on a jug or drinking glass. Foodstuff residues are moved forwardly to push outward the elastic ring 17 and to move out of the tubular main body 11 for discharge after passing through a gap between the guide exit section 215 and the annular flange 15.
However, the design of the grinding and extracting device of the existing food processor has the following drawbacks that need to be improved:
First, since a thread depth of the guide thread 22 that protrudes radially from the guide entry section 211 is uniform and a gap between the guide thread 22 and the support screen plate 14 is relatively narrow, when cutting and guiding the foodstuff, the foodstuff is likely to get stuck in the gap, so that the spindle 2 receives a large rotational resistance and cannot rotate smoothly. As such, the load of the drive unit is relatively increased. Hence, the drive unit is easy to break down.
Second, because gaps between the filter threads 25 and the filter member 16 are large and because a screw lead of the filter threads 25 is equal to four times the pitch, the distance between each filter thread 25 is large, so that the processed foodstuff and the residues cannot be uniformly distributed among the filter threads 25. That is, some of the gaps are squeezed with more residues, while others are squeezed with less residues or are free from residues. As a result, the spindle 2 cannot be steadily held in the tubular member 1, but shakes and produces noise during rotation.
Third, the diameter of the spindle 2 changes abruptly from a rear side to a front side thereof, and only the protruding portion between the crushing section 212 and the grinding section 213 is adjacent to the metal ring 13, so that the main grinding process of the foodstuff is concentrated and accomplished in said portion. In this manner, the metal ring 13 bears the largest squeezing force, and the foodstuff is easily accumulated between the grinding section 213 and the metal ring 13. Not only is the rotation of the spindle 2 difficult, but also the foodstuff cannot be uniformly ground. As a result, the efficiency of juice extraction is low. In addition, because an annular gap 18 is formed between the metal ring 13 and the filter member 16 such that the foodstuff and the residues are easily stuck in the gap 18, a portion of the tubular main body 11 that corresponds to the gap 18 bears a strong squeezing force, causing the portion of the tubular main body 11 to crack and damage. Thus, the service life of the tubular member 1 is shortened.
Fourth, because the elastic ring 17 is fixedly connected to the inside of the annular flange 15, when the elastic ring is damaged or deteriorated, the whole tubular member 1 must be removed and replaced with a new one.